1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Amlogic Meson6, Meson8 and Meson8b eFuse Driver
4  *
5  * Copyright (c) 2017 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
6  */
7 
8 #include <linux/bitfield.h>
9 #include <linux/bitops.h>
10 #include <linux/clk.h>
11 #include <linux/delay.h>
12 #include <linux/io.h>
13 #include <linux/iopoll.h>
14 #include <linux/module.h>
15 #include <linux/nvmem-provider.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/sizes.h>
19 #include <linux/slab.h>
20 
21 #define MESON_MX_EFUSE_CNTL1					0x04
22 #define MESON_MX_EFUSE_CNTL1_PD_ENABLE				BIT(27)
23 #define MESON_MX_EFUSE_CNTL1_AUTO_RD_BUSY			BIT(26)
24 #define MESON_MX_EFUSE_CNTL1_AUTO_RD_START			BIT(25)
25 #define MESON_MX_EFUSE_CNTL1_AUTO_RD_ENABLE			BIT(24)
26 #define MESON_MX_EFUSE_CNTL1_BYTE_WR_DATA			GENMASK(23, 16)
27 #define MESON_MX_EFUSE_CNTL1_AUTO_WR_BUSY			BIT(14)
28 #define MESON_MX_EFUSE_CNTL1_AUTO_WR_START			BIT(13)
29 #define MESON_MX_EFUSE_CNTL1_AUTO_WR_ENABLE			BIT(12)
30 #define MESON_MX_EFUSE_CNTL1_BYTE_ADDR_SET			BIT(11)
31 #define MESON_MX_EFUSE_CNTL1_BYTE_ADDR_MASK			GENMASK(10, 0)
32 
33 #define MESON_MX_EFUSE_CNTL2					0x08
34 
35 #define MESON_MX_EFUSE_CNTL4					0x10
36 #define MESON_MX_EFUSE_CNTL4_ENCRYPT_ENABLE			BIT(10)
37 
38 struct meson_mx_efuse_platform_data {
39 	const char *name;
40 	unsigned int word_size;
41 };
42 
43 struct meson_mx_efuse {
44 	void __iomem *base;
45 	struct clk *core_clk;
46 	struct nvmem_device *nvmem;
47 	struct nvmem_config config;
48 };
49 
50 static void meson_mx_efuse_mask_bits(struct meson_mx_efuse *efuse, u32 reg,
51 				     u32 mask, u32 set)
52 {
53 	u32 data;
54 
55 	data = readl(efuse->base + reg);
56 	data &= ~mask;
57 	data |= (set & mask);
58 
59 	writel(data, efuse->base + reg);
60 }
61 
62 static int meson_mx_efuse_hw_enable(struct meson_mx_efuse *efuse)
63 {
64 	int err;
65 
66 	err = clk_prepare_enable(efuse->core_clk);
67 	if (err)
68 		return err;
69 
70 	/* power up the efuse */
71 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
72 				 MESON_MX_EFUSE_CNTL1_PD_ENABLE, 0);
73 
74 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL4,
75 				 MESON_MX_EFUSE_CNTL4_ENCRYPT_ENABLE, 0);
76 
77 	return 0;
78 }
79 
80 static void meson_mx_efuse_hw_disable(struct meson_mx_efuse *efuse)
81 {
82 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
83 				 MESON_MX_EFUSE_CNTL1_PD_ENABLE,
84 				 MESON_MX_EFUSE_CNTL1_PD_ENABLE);
85 
86 	clk_disable_unprepare(efuse->core_clk);
87 }
88 
89 static int meson_mx_efuse_read_addr(struct meson_mx_efuse *efuse,
90 				    unsigned int addr, u32 *value)
91 {
92 	int err;
93 	u32 regval;
94 
95 	/* write the address to read */
96 	regval = FIELD_PREP(MESON_MX_EFUSE_CNTL1_BYTE_ADDR_MASK, addr);
97 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
98 				 MESON_MX_EFUSE_CNTL1_BYTE_ADDR_MASK, regval);
99 
100 	/* inform the hardware that we changed the address */
101 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
102 				 MESON_MX_EFUSE_CNTL1_BYTE_ADDR_SET,
103 				 MESON_MX_EFUSE_CNTL1_BYTE_ADDR_SET);
104 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
105 				 MESON_MX_EFUSE_CNTL1_BYTE_ADDR_SET, 0);
106 
107 	/* start the read process */
108 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
109 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_START,
110 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_START);
111 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
112 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_START, 0);
113 
114 	/*
115 	 * perform a dummy read to ensure that the HW has the RD_BUSY bit set
116 	 * when polling for the status below.
117 	 */
118 	readl(efuse->base + MESON_MX_EFUSE_CNTL1);
119 
120 	err = readl_poll_timeout_atomic(efuse->base + MESON_MX_EFUSE_CNTL1,
121 			regval,
122 			(!(regval & MESON_MX_EFUSE_CNTL1_AUTO_RD_BUSY)),
123 			1, 1000);
124 	if (err) {
125 		dev_err(efuse->config.dev,
126 			"Timeout while reading efuse address %u\n", addr);
127 		return err;
128 	}
129 
130 	*value = readl(efuse->base + MESON_MX_EFUSE_CNTL2);
131 
132 	return 0;
133 }
134 
135 static int meson_mx_efuse_read(void *context, unsigned int offset,
136 			       void *buf, size_t bytes)
137 {
138 	struct meson_mx_efuse *efuse = context;
139 	u32 tmp;
140 	int err, i, addr;
141 
142 	err = meson_mx_efuse_hw_enable(efuse);
143 	if (err)
144 		return err;
145 
146 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
147 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_ENABLE,
148 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_ENABLE);
149 
150 	for (i = 0; i < bytes; i += efuse->config.word_size) {
151 		addr = (offset + i) / efuse->config.word_size;
152 
153 		err = meson_mx_efuse_read_addr(efuse, addr, &tmp);
154 		if (err)
155 			break;
156 
157 		memcpy(buf + i, &tmp,
158 		       min_t(size_t, bytes - i, efuse->config.word_size));
159 	}
160 
161 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
162 				 MESON_MX_EFUSE_CNTL1_AUTO_RD_ENABLE, 0);
163 
164 	meson_mx_efuse_hw_disable(efuse);
165 
166 	return err;
167 }
168 
169 static const struct meson_mx_efuse_platform_data meson6_efuse_data = {
170 	.name = "meson6-efuse",
171 	.word_size = 1,
172 };
173 
174 static const struct meson_mx_efuse_platform_data meson8_efuse_data = {
175 	.name = "meson8-efuse",
176 	.word_size = 4,
177 };
178 
179 static const struct meson_mx_efuse_platform_data meson8b_efuse_data = {
180 	.name = "meson8b-efuse",
181 	.word_size = 4,
182 };
183 
184 static const struct of_device_id meson_mx_efuse_match[] = {
185 	{ .compatible = "amlogic,meson6-efuse", .data = &meson6_efuse_data },
186 	{ .compatible = "amlogic,meson8-efuse", .data = &meson8_efuse_data },
187 	{ .compatible = "amlogic,meson8b-efuse", .data = &meson8b_efuse_data },
188 	{ /* sentinel */ },
189 };
190 MODULE_DEVICE_TABLE(of, meson_mx_efuse_match);
191 
192 static int meson_mx_efuse_probe(struct platform_device *pdev)
193 {
194 	const struct meson_mx_efuse_platform_data *drvdata;
195 	struct meson_mx_efuse *efuse;
196 
197 	drvdata = of_device_get_match_data(&pdev->dev);
198 	if (!drvdata)
199 		return -EINVAL;
200 
201 	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
202 	if (!efuse)
203 		return -ENOMEM;
204 
205 	efuse->base = devm_platform_ioremap_resource(pdev, 0);
206 	if (IS_ERR(efuse->base))
207 		return PTR_ERR(efuse->base);
208 
209 	efuse->config.name = drvdata->name;
210 	efuse->config.owner = THIS_MODULE;
211 	efuse->config.dev = &pdev->dev;
212 	efuse->config.priv = efuse;
213 	efuse->config.stride = drvdata->word_size;
214 	efuse->config.word_size = drvdata->word_size;
215 	efuse->config.size = SZ_512;
216 	efuse->config.read_only = true;
217 	efuse->config.reg_read = meson_mx_efuse_read;
218 
219 	efuse->core_clk = devm_clk_get(&pdev->dev, "core");
220 	if (IS_ERR(efuse->core_clk)) {
221 		dev_err(&pdev->dev, "Failed to get core clock\n");
222 		return PTR_ERR(efuse->core_clk);
223 	}
224 
225 	efuse->nvmem = devm_nvmem_register(&pdev->dev, &efuse->config);
226 
227 	return PTR_ERR_OR_ZERO(efuse->nvmem);
228 }
229 
230 static struct platform_driver meson_mx_efuse_driver = {
231 	.probe = meson_mx_efuse_probe,
232 	.driver = {
233 		.name = "meson-mx-efuse",
234 		.of_match_table = meson_mx_efuse_match,
235 	},
236 };
237 
238 module_platform_driver(meson_mx_efuse_driver);
239 
240 MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
241 MODULE_DESCRIPTION("Amlogic Meson MX eFuse NVMEM driver");
242 MODULE_LICENSE("GPL v2");
243